how to clear txt file when you exit your application c#

Question

this is my code to fill my txt file, and show in my application.

StreamWriter file = new StreamWriter("opslag_kentekens",true);
string opslag_kentekens = textBox1.Text;
file.WriteLine(opslag_kentekens);
file.Close();

label20.Text = File.ReadAllText("opslag_kentekens");

My question is: how do i clear my txt file when i exit my application?

Answer 1

Clearing of text file is pretty straightforward: just write empty string into it:

StreamWriter file = new StreamWriter("opslag_kentekens", false);
file.Write(String.Empty);
file.Close();

Catching application exit depends on framework you're using in your application.

For example, on WinForms (it looks like you're using it) you can override OnFormClosed method of your main application form and to your file clearing there:

protected override void OnFormClosed(FormClosedEventArgs e)
{
    base.OnFormClosed(e);

    //clear your file
}

Or you can handle Application.ApplicationExit event and clear your file from there.